MAGNETIC-SUSCEPTIBILITY OF A SEMICONDUCTOR SUPERLATTICE UNDER PARALLEL ELECTRIC AND MAGNETIC-FIELDS

We have calculated the magnetic susceptibility chi of the degenerate e lectron gas in a semiconductor superlattice placed in parallel quantiz ing electric (E) and magnetic (H) fields directed along the superlatti ce growth axis. In this case the electrons have a purely discrete ener gy spectrum consisting of Landau and Wannier-Stark levels. This leads to: (i) the dependence of the monotonic part of the diamagnetic suscep tibility of the electron gas on the electric field; (ii) the rise of a new oscillation period of chi as a function of H different from that of the de Haas-van Alphen oscillations; and (iii) the oscillatory beha viour of chi as a function of E with a periodicity in square-root E. I t is shown that in weak magnetic fields the Wannier-Stark quantization results in a step-like dependence of the paramagnetic susceptibility of the electron gas on the electric field strength.